It's so hard to reduce this to just 40, but I'll give it a go.
1. Maybe I'm Amazed
2. Band on the Run
3. Junk/Singalong Junk
4. Calico Skies
5. Uncle Albert/Admiral Halsey
6. Another Day
7. Every Night
8. Venus and Mars/Rock Show
9. Mrs Vanderbilt
10. My Love
11. The Pound is Sinking
12. Call Me Back Again
13. Dear Friend
14. Heart of the Country
15. My Brave Face
16. Jenny Wren
17. Too Many People
18. Let Me Roll It
19. Live and Let Die
20. Big Barn Bed
21. Nineteen Hundred and Eighty Five
22. Little Woman Love
23. C Moon
24. Jet
25. Love in Song
26. Hi Hi Hi
27. Tomorrow
28. One of These Days
29. The Lovers That Never Were (demo version)
30. No More Lonely Nights
31. Bluebird
32. Junior's Farm
33. Winter Rose/Love Awake
34. Ballroom Dancing
35. Here Today
36. Take It Away
37. Monkberry Moon Delight
38. Back Seat of My Car
39. Soily (live version)
40. Daytime Nighttime Suffering
I've had to leave out so many great songs. The older songs outnumber the more recent songs, but I can't help that - those are the songs I grew up with. And my two favourite Beatles era demos (which are almost solo) are the lovely voice/guitar demo of Goodbye for Mary Hopkin, and the one-man band demo of Come and Get It for Badfinger (both of those are gems).